1. Field of the Invention
The present invention relates to a method of doping by diffusing silicon into Group III-V compound semiconductors such as GaAs and AlGaAs, a semiconductor device having a doped layer formed by same doping method, and a method of fabricating same semiconductor device.
2. Description of Related Art
Diffusion and ion implantation, as well as crystal growth techniques, are well known methods of doping semiconductor substrates with impurities. In particular, for silicon, (Si) devices using Si substrates, diffusion and ion implantation have been established as important techniques for introducing dopants into Si substrates.
On the other hand, in the case of Group III-V compound semiconductors such as GaAs, GaP, InP, etc., impurity doping has involved the intrinsic problem that the stoichiometric composition of the substrate crystal tends to be upset when subject to high processing temperatures, which has lead to the necessity of developing doping methods suitable for individual kinds of substrates. Up to date, however, only part of such methods have been established. For GaAs substrates, for example, ion implantation and a part of diffusion (Zn diffusion to form a p-type impurity layer) are the only established techniques for practical use. A diffusion method for forming an n-type impurity layer has not yet been established for GaAs substrates primarily because the stoichiometric composition of the GaAs substrate crystal tends to be dislocated due to dissociation of As because of high diffusion temperatures (800.degree. C. and higher) and the diffusion, therefore, cannot be preformed in a well controlled manner.